<!DOCTYPE html>
<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
<style>
  @page {
    size: 650px 500px;
    margin: 0;
  }
  body {
    margin: 0;
  }
  .grid {
    display: grid;
    grid-template-columns: 100px auto 100px;
    grid-template-rows: 100px auto 100px;
    height: 100vh;
  }
  .vertical-edge {
    display: flex;
  }
  .horizontal-edge {
    display: flex;
    flex-flow: column;
  }
</style>
<div class="grid">
  <div class="corner"></div>
  <div class="vertical-edge">
    <div style="width:150px; background:hotpink;"></div>
    <div style="width:150px; background:cyan;"></div>
    <div style="width:150px; background:yellow;"></div>
  </div>
  <div class="corner"></div>
  <div class="horizontal-edge">
    <div style="height:100px; background:yellow;"></div>
    <div style="height:100px; background:cyan;"></div>
    <div style="height:100px; background:hotpink;"></div>
  </div>
  <div></div>
  <div class="horizontal-edge">
    <div style="height:300px; background:cyan;"></div>
  </div>
  <div class="corner"></div>
  <div class="vertical-edge">
    <div style="width:225px; background:hotpink;"></div>
    <div style="width:225px; background:yellow;"></div>
  </div>
  <div class="corner"></div>
</div>
